Conventional ultrasound imaging equipment measures range and only one angle to produce a two dimensional slice through the organ being monitored. Typically, it produces a slice consisting of 256 lines in a {fraction (1/30)} th of a second time frame. For each depth, this gives 256 picture elements or pixels per slice, one slice per frame. The difficulty that arises in three-dimensional imaging is that N slices require N2 lines as opposed to N. A solution is to form many lines at a time.
Three dimensional ultrasound imaging systems currently exist, allowing any slice, at any orientation, to be displayed at the discretion of the user. For example, a particular system presently available employs a transmitter beam that insonifies a 4 by 4 array of 16 receiver beams. Since 16 beams are formed for each transmitted pulse, 16xc3x97256 lines are produced in each frame. This allows for the formation of a three dimensional image in a single frame, with a 64 by 64 array of pixels for each depth. However, this array of pixels limits the resolution of any 3D image produced with this system.
An ultrasonic device set forth in WO 00/072,756 , which is hereby incorporated by reference in its entirety, provides for far more receive beams per pulse. In particular, an N by N receiver array described in the WO 00/072,756 application can provide (N/2)2 simultaneous receive beams. Thus, choosing N=16, for example, produces an 8 by 8 array of 64 receiver beams for each transmitted pulse. Moreover, a device of the WO 00/072,756 application utilizes a planar array of rectangular ultrasound transducer elements comprising multiple transmitters and a thinned receiver array (elements are spaced more than xc2xd wavelength apart). A subset of the total aperture is used to transmit for a given time and insonate a number of receive beam positions without insonating the receiver grating lobes that result from thinning. In order to perform 3-dimensional ultrasound imaging, with a meaningful number of lines in two angular dimensions (called azimuth and elevation), it is necessary to scan a wide transmit beam so as to cover, say, a 90xc2x0 sector (xc2x145xc2x0) in both azimuth and elevation.
Thus, a device as described in the WO 00/072,756 application allows for a 128xc3x97128 array of pixels for each depth. Furthermore, a device of the WO 00/072,756 application utilizes a thinned array, reducing the number of array elements and resulting in far less cabling and input electronics.
However, a thinned array described in the WO 00/072,756 application has limited applications in evaluating a large volume of a subject""s body. Thus, in order to make such an evaluation, it may be necessary to take data from a particular segment of the subject""s body, and then physically move the thinned array to an adjacent segment for additional data taking.
Accordingly, what is needed is a thinned array that permits high-resolution imaging of a large volume a subject""s body, without the necessity of relocating the array. Such a thinned array would improve the performance of presently known ultrasound devices, and further permit their use in fields such as cardiac diagnosis and monitoring.
What is also needed is a thinned array that has applications with any presently available or subsequently discovered ultrasound device.
What is also needed is a thinned array that is configured to suppress, or at least severely limit spatial ambiguities, or xe2x80x9cgrating lobesxe2x80x9d that would interfere with the application of an ultrasound device, and decrease the resolution of a three dimensional image generated from echoes received from the subject""s body.
The citation of any reference herein should not be construed as an admission that such reference is available as xe2x80x9cPrior Artxe2x80x9d to the instant application.
There is provided, in accordance with the present invention a novel, useful, and unobvious thinned array for use with an ultrasound device, that offers the advantage of permitting high-resolution imaging of a large volume of a subject""s body.
Broadly, the present invention extends to a thinned array for use with an ultrasound device for evaluating a volume of a subject""s body, wherein the volume is formed of a plurality of segments. Such a thinned array comprises:
(a) a plurality of transmitters configured so that one transmitter insonates one individual segment of the volume at a time; and
(b) an array of receivers that simultaneously receive echoes from the volume being evaluated, wherein the array of receivers is electronically aimed and dynamically focused upon sub-segments of the insonated segment of the volume, wherein the spacing among the receivers in the array is greater than xc2xd the wavelength of the ultrasonic energy produced by the transmitters, and the receivers are configured to receive echoes from the sub-segments of the individual insonated segments of the volume of the subject""s body in a pattern that is aligned with the insonated segment of the volume insonated by the transmitters, so that receiver grating lobes nearest the echoes coincide with first transmitter nulls, and the deleterious effects of grating lobes are minimized.
In a particular embodiment, the transmitters and receivers of a thinned array of the present invention are in a two-dimensional configuration. The shape of the transmitters can vary. Particular examples include, but certainly are not limited to rectangles, e.g., a square, and diamond shapes. In an embodiment wherein the transmitters are rectangular in shape, the transmitters are positioned flush against each.
As explained above a thinned array of the present invention also comprises a plurality of receivers that simultaneously receive echoes from the volume being evaluated, wherein the spacing of the receivers is greater than xc2xd the wavelength of the sonic energy produced by the transmitters. In a particular embodiment of the present invention, wherein the transmitters are diamond in shape, the receivers can optionally be interleaved with the transmitters.
Naturally, a thinned array of the present invention is electronically connected to a particular ultrasound device utilizing the thinned array.
Thus, a thinned (greater than xc2xd wavelength element spacing) array of ultrasound transducers of the present invention is used to form a large number of received and focused beams within an insonated volume. Since array thinning allows for scanning or imaging over only a limited region or segment, a set of transmitters are fired one at a time to insonate one segment at a time. The receiver is an array of receiver elements, all receiving simultaneously echoes from the volume of the subject""s body insonated by the transmitters one at a time. A novel aspect of the present invention, wherein each particular transmitter insonates a segment of the volume subject""s body, permits the insonation and evaluation of a larger volume the subject""s body than can be evaluated with heretofore known thinned arrays. A large number of receive beams are formed digitally for each transmitted pulse, and each transmitter is designed to provide very little energy in the direction of undesired receiver spatial ambiguities or xe2x80x9cgrating lobesxe2x80x9d.
In another embodiment, the present invention extends to a thinned array for use with an ultrasound device for evaluating a volume of a subject""s body, comprising:
(a) an array of transmitters having spacing that is greater than xc2xd the wavelength of the ultrasonic energy produced by the transmitters, and the array of transmitters are configured to insonate sub-segments of segments of the volume of the subject""s body being evaluated, so that transmitter grating lobes coincide with first receiver nulls so that deleterious effects of grating lobes are minimized, and the array electronically scans the segments of the volume of the subject""s body being evaluated, one sub-segment at a time; and
(b) a plurality of receivers that simultaneously receive echoes from the sub-segments of the segments of the volume of the subject being evaluated, wherein each receiver points to a particular grating lobe of the transmitter pattern, or to a particular segment of volume.
Naturally, a thinned array of the present invention is electronically connected to a particular ultrasound device utilizing the thinned array.
Furthermore, the present invention extends to a method for insonating a volume of a subject with a thinned array for use with an ultrasound device, comprising the steps of:
(a) providing a thinned array for evaluating a volume of a subject""s body, the thinned array comprising:
(i) a plurality of transmitters configured so that one transmitter insonates one individual segment of the volume at a time; and
(ii) an array of receivers that simultaneously receive echoes from the volume being evaluated, wherein the array of receivers is electronically aimed and dynamically focused upon sub-segments of the insonated segment of the volume, wherein the spacing among the receivers in the array is greater than xc2xd the wavelength of the ultrasonic energy produced by the transmitters, and the receivers are configured to receive echoes from the sub-segments of the individual insonated segments of the-volume of the subject""s body in a pattern that is aligned with the insonated segment of the volume insonated by the transmitters, so that receiver grating lobes nearest the echoes coincide with first transmitter nulls, and the deleterious effects of grating lobes are minimized; and
(b) electrically connecting the thinned array to the ultrasound device, so that the volume of the subject can be ultrasonically evaluated.
Moreover, the present invention extends to a method for insonating a volume of a subject with a thinned array for use with an ultrasound device, comprising the steps of:
(a) providing a thinned array for evaluating a volume of a subject""s body, the thinned array comprising:
(i) an array of transmitters having spacing that is greater than xc2xd the wavelength of the ultrasonic energy produced by the transmitters, and the array of transmitters are configured to insonate sub-segments of segments of the volume of the subject""s body being evaluated, so that transmitter grating lobes coincide with first receiver nulls so that deleterious effects of grating lobes are minimized, and the array electronically scans the segments of the volume of the subject""s body being evaluated, one sub-segment at a time; and
(ii) a plurality of receivers that simultaneously receive echoes from the sub-segments of the segments of the volume of the subject being evaluated, wherein each receiver points to a particular grating lobe of the transmitter pattern, or to a particular segment of volume; and
(b) electrically connecting the thinned array to the ultrasound device, so that the volume of the subject can be ultrasonically evaluated.
Accordingly, it is an object of the present invention to provide a novel and useful thinned array that permits high-resolution imaging of a large volume a subject""s body, without the necessity of relocating the array.
It is another object of the present invention to provide a novel and useful thinned array that can be readily utilized with any presently known or subsequently developed ultrasound device.
It is yet another object of the present invention to provide a novel and useful thinned array that is configured to suppress, or at least substantially reduce grating lobes.
These and other aspects of the present invention will be better appreciated by reference to the following drawings and Detailed Description.